Particularly in the case of young patients, or patients in whom the bone substance is well preserved, care must be taken that as little bone substance as possible is lost when fitting a shoulder prosthesis. Another important requirement is that mobility be preserved, while at the same time maintaining joint stability.
Already known in this regard are so-called cup shoulder prostheses which are offered by, among others, the companies Centerpulse and Biomet Orthopedics. With these so-called cup shoulder prostheses, the head component is fixed to the joint head bone, with or without bone cement, by means of a shaft located medially within a cap-like head. Accessibility to the joint socket is thus significantly impeded due to the fact that the joint head is essentially maintained. As a result, the necessary socket-restorative appliance is omitted.